1. Field of the Invention
The present invention relates to a cable assembly for drilling and mining type cables. More particularly, the present invention relates to a cable assembly, and method for making the same, for drilling and mining type cables, which are not encased in a protective outer hose.
2. Description of Related Art
A dynamic application cable assembly, as differentiated from a static application cable, is one which may be subjected to one or more cyclical or continual forces such as bending, twisting, tension, compression, thermal loading, external pressure, and the like.
Examples of such dynamic cable assemblies include top drive service loop cable assemblies for drilling rigs, bridle cable assemblies used on offshore tender vessels, and shuttle car cable assemblies used in mining operations. These large dynamic application cables typically include a combination of electrical wires, hydraulic lines and fiber optic cables. For protection, the cables are fitted into a large diameter rubber hose which is often reinforced with steel wires or synthetic fibers. Within this hose there is typically a potting material to support the cable components against the inside diameter of the hose as shown for example in the prior art FIGS. 1 and 2.
However, such designs are very heavy and relatively inflexible. In addition, they typically have a large outer diameter which often limits the effective bending radius of the assembly. While the prior art designs are workable, they are not ideal for the dynamic applications in which they are used. These cable assemblies are repeatedly subjected to moving forces, particularly bending and flexing, in which the size, weight, and relative stiffness of the assembly often limits its effective run life. Since the cable assembly is a vital link in the operation of the equipment to which it is connected, the cost of reduced run life of the assembly may be measured in the cost of down-time in the associated equipment. Especially in drilling and mining operations this translates into lost production, and typically hundreds of thousands of dollars per day in lost revenues.
Additionally, these designs are generally not field-repairable and in most cases the cable assembly must be replaced when it is damaged. This has the potential impact of extending the down-time of the operation even further.
The need exists for a lighter, smaller, and more flexible cable assembly which may be temporarily repaired in the field. Not only will such a design improve the assembly's run life, but it will also meet the ever-harsher environments and dynamic applications in which such an assembly is applied.